1. Field of the Invention
The invention relates to a neuro-navigation system comprising a reflector referencing system including passive reflectors and a marker system with markers or landmarks wherein the reflectors as well as the markers as regards their shape, size and material selection as well as their arrangement or attachment on the parts of the body to be operatively treated and on the surgical instruments are configured so that mapping their locations is substantially facilitated or is able to take place more accurately positioned by a computer/camera unit having a graphic display terminal as well as the operative treatment with the aid of this unit. Optionally a surgical microscope, an ultrasonic diagnostic system as well as a calibration procedure may be integrated in the Neuro-navigation system in accordance with the invention.
2. Description of the Prior Art
Neuro-navigation systems represent the link between the surgeon carrying out the operation, i.e. the anatomy of the patient as seen by the surgeon for operative treatment and diagnostic data furnished, for example, by computer tomography and visually displayed by the display terminal of a computer unit.
To produce this link, i.e. to render the momentary positional data of the anatomy of the patient and that of the surgical instruments and apparatus employed in the operation visible on the display terminal of the computer, devices need to be made available which are capable of mapping the position of the patient and thus the precise location of the parts of the body to be operatively treated as well as the location of the surgical instruments and, more particularly, the tips thereof in a starting position and to keep track of them during the operation.
For this purpose conventionally a computer unit is made available, to which two or more referencing cameras are connected. With these cameras both the position of artificial or natural landmarks affixed to the patient as well as the position of radiative emitters applied to the surgical instruments are mapped.
The procedure as regards the landmarks affixed to the patient on systems hitherto is as follows:
Prior to implementing computer tomography a set of artificial landmarks is affixed to the patient surrounding the zone to be operatively treated. These landmarks which can be mapped by the cameras in both the computer tomography as well as later in the operation are totally identical to each other, they being affixed to the patient by sticky plaster, for example.
After this treatment the data of the computer tomography, i.e. both the positional data of the artificial landmarks each identical to the other and the position of the operation target and the surrounding areas are entered into the computer system which together with the referencing or mapping cameras is arranged on the operating table. This is followed by a time-consuming step in which the surgeon needs to access the individual landmarks on the patient with a pointer, he then having to enter into the computer which of the identical landmarks in the operating position correspond to those sensed in the computer tomography. For this purpose all landmarks need to be accessed a number of times, followed each time by the time-consuming manual assignment to the computer tomography (CT) data. Since the landmarks secured by sticky plaster fail to comprise characteristical reference points, which cannot be missed in accessing them with an instrument tip, mapping in this respect can only take place relatively inaccurately.
A further disadvantage in this respect is that the conventional landmarks, once covered with sterile cloths, are no longer directly discernible, because of their flat configuration, and thus can no longer be accessed precisely in position should the patient already be covered. This causes problems particularly later on when the position of the patient is changed during the operation and the landmarks need to be reaccessed with the pointer for a readjustment.
Furthermore, it is a disadvantage that the known landmarks, once affixed to the patient, are no longer removable by being able to be replaced by other landmarks in precisely the same position.
Conventional emitter systems for surgical instruments and apparatus employed in the operation are configured as follows:
Two or more active emitters, emitting, for example, beams of infrared radiation, are applied to each instrument or operation apparatus and act as spot emitters located on a surface area. In the instrument an electronic device is provided permitting emission of the signals, the instrument being connected at its rear end by a cable to the computer unit. Due to the emitted signals the computer unit is able to identify the three-dimensional position of the instruments or the tips thereof.
This conventional instrument referencing system is also hampered by several drawbacks as explained in the following. Using active, i.e. self-emitting signal transmitters already has the disadvantage that electronic means need to be provided in the instruments which makes particularly the manufacture of such instruments more expensive. In addition, the cables attached to each instrument connecting it to the computer unit are an obstruction to movement and can get in the way during the operative treatment due to the many instruments often to be used.
The emitters attached as points to a surface area of the instrument can be “seen” only in a very restricted angular viewing range of the camera system, i.e. they may easily be concealed by the instrument itself or by the hand of the surgeon.
Sterilization of such instruments can only be done by gas sterilization. Such a gas sterilization may last up to a whole day, as a result of which several sets of instruments need to be purchased to ensure that sterilized instruments are available for operative treatment at all times when often required.
One serious drawback of the conventional referencing system is that the surgeon is only able to use exclusively the instruments made available by the system manufacturer. Many surgeons are, however, used to their own set of instruments and need to adapt when using another specified set of instruments which may have a negative effect on the outcome of the operation.
It is a disadvantage that conventional Neuro-navigation systems fail to provide a simple calibration system with which the angles or spacing of the mapping or referencing cameras can be mapped or recalibrated at any time without complication. Since these cameras are often subject to a change in position during the operation due to, for example, one of the persons carrying out the operative treatment jolting the camera stand, speedy and easy recalibration during the operation is of major importance.
In a neurosurgical operation it is often the case that a surgical microscope is used. Such microscopes are conventionally mounted on a heavy base and frame, the actual microscope as such being secured to the end of an articulated arm permitting powered and manual positional shifting of the microscope and signalling the positional data, for example, in sensing the angular position of the arm joints for feedback to a computer unit used in Neuro-navigation.
The bases or stands of such microscopes need to be configured very heavy and safe-standing to prevent, for instance, jolting the microscope from possibly changing its position, thus ruining Neuro-navigation of the microscope calibrated at the outset to the starting position. Microscopes are namely conventionally unable to output any additional position feedback signals to the Neuro-navigation computer other than the positional data resulting from the position of the arm.
In conclusion, it is often the case in neurosurgical operations that ultrasonic diagnostic systems, as known, for instance, in examination during a pregnancy, find application. It has hitherto been a drawback in the case of conventional systems that although the position of the sensed parts of the body could be related to the ultrasonic emitter and detector, there was no possibility of simply assigning this data to a Neuro-navigation system made available on the operating table.